HERAT -- More than 500 angry demonstrators have gathered in the western Afghan city of Herat to protest Iran's decision to bar fuel tankers from entering their country.

They also accused Iranian President Mahmud Ahmadinejad's government of mistreating Afghan refugees.

Afghan officials say Tehran has been allowing only small numbers of trucks to cross the border in Afghanistan, stranding hundreds of tankers at the border for weeks.

Protesters, gathered outside Iran's diplomatic mission in Herat, told RFE/RL's Afghan Service that Iran's actions have created painful fuel shortages at a time of high demand during winter.

"Iran is oppressing the Afghan people and is stopping fuel tankers at the border despite the cold winter," one man said. "The owners of the tankers have to pay Iranians between $100 and $150 per night spent at the border. We've also heard that Iranian soldiers were stealing oil from the tankers. We condemn this."

Another said protesters were trying to send a message of solidarity as Kabul seeks to get the blockade ended.

"We want President Karzai to know that the Afghan nation supports him. Afghanistan has a long history, and Iran has never dared interfere like this," he said.

Some Afghan lawmakers claim dozens of Afghans have been executed on such charges in recent weeks.

Iran has summoned the Afghan ambassador in Tehran to protest the demonstrations.

Similar rallies have been taking place across Afghanistan in recent days, including a demonstration today in the city of Gardez, in the Paktika Province.

Mohammad Naeem, a taxi driver in the southern Afghan city of Kandahar, says soaring fuel prices have deprived him of his livelihood.

"What else can we do, there is no other work we can engage in," Naeem said. "This government has not built any factories or created any other work opportunities for us. This taxi is my only source of income, and it's increasingly difficult to live off it."

Iran has said the slowdown was due to "technical problems."

But some Afghan officials suggest that Iran could be blocking fuel exports to Afghanistan out of concern that the fuel is being funneled to NATO forces fighting the Taliban.